1. Field of the Invention
The present invention relates to compounds of the formula I and their physiologically tolerable salts and pharmaceutical preparations comprising such compounds, their preparation and use as medicaments, in particular as inhibitors of bone resorption by osteoclasts, as inhibitors of tumor growth and tumor metastasis, as antiinflammatories, for the treatment or prophylaxis of cardiovascular disorders such as arteriosclerosis or restenosis, for the treatment or prophylaxis of nephropathies and retinopathies, such as, for example, diabetic retinopathy, and as vitronectin receptor antagonists for the treatment and prophylaxis of illnesses which are based on the interaction between vitronectin receptors and their ligands in cell--cell or cell-matrix interaction processes. The invention furthermore relates to the use of the compounds of the formula I and their physiologically tolerable salts and pharmaceutical preparations comprising those compounds as medicaments for the alleviation or cure of illnesses which are caused at least partially by an undesired extent of bone resorption, angiogenesis, or proliferation of cells of the vascular smooth musculature.
2. Description of Related Art
Human bones undergo a continuous dynamic renovation process which involves bone resorption and bone formation. These processes are controlled by types of cell specialized for this. Bone formation is based on the deposition of bone matrix by osteoclasts, bone resorption is based on the degradation of bone matrix by osteoclasts. The majority of bone disorders are based on a disturbed equilibrium between bone formation and bone resorption. Osteoporosis is characterized by a loss of bone matrix. Activated osteoclasts are polynuclear cells having a diameter of up to 400 .mu.m, which remove bone matrix. Activated osteoclasts accumulate on the surface of the bone matrix and secrete proteolytic enzymes and acids into the so-called "sealing zone", the region between their cell membrane and the bone matrix. The acid environment and the proteases bring about the degradation of the bone.
Studies have shown that the accumulation of osteoclasts on the bone is controlled by integrin receptors on the cell surface of osteoclasts.
Integrins are a superfamily of receptors which include, inter alia, the fibrinogen receptor .alpha..sub.IIb .beta..sub.3 on the blood platelets and the vitronectin receptor .alpha..sub.v .beta..sub.3. The vitronectin receptor .alpha..sub.v .beta..sub.3 is a membrane glycoprotein which is expressed on the cell surface of a number of cells such as endothelial cells, cells of the vascular smooth musculature, osteoclasts and tumor cells. The vitronectin receptor .alpha..sub.v .beta..sub.3 which is expressed on the osteoclast membrane controls the process of accumulation on the bone and bone resorption and thus contributes to osteoporosis.
.alpha..sub.v .beta..sub.3 in this case binds to bone matrix proteins such as osteopontin, bone sialoprotein and thrombospontin, which contain the tripeptide motif Arg-Gly-Asp (or RGD).
Horton and co-workers describe RGD peptides and an anti-vitronectin receptor antibody (23C6), which inhibit tooth destruction by osteoclasts and the migration of osteoclasts (Horton et al., Exp. Cell. Res. 1991, 195, 368). In J. Cell Biol. 1990, 111, 1713, Sato et al. describe echistatin, an RGD peptide from snake venom, as a potent inhibitor of bone resorption in a tissue culture and as an inhibitor of osteoclast attachment to the bone. Fischer et al. (Endocrinology, 1993, 132, 1411) were able to show in the rat that echistatin also inhibits bone resorption in vivo.
The vitronectin receptor .alpha..sub.v .beta..sub.3 on human cells of the vascular smooth musculature of the aorta stimulates the migration of these cells into the neointima, which finally leads to arteriosclerosis and restenosis after angioplasty (Brown et al., Cardiovascular Res. 1994, 28, 1815).
Brooks et al. (Cell 1994, 79, 1157) show that antibodies against .alpha..sub.v .beta..sub.3 or .alpha..sub.v .beta..sub.3 antagonists can bring about a shrinkage of tumors by inducing the apoptosis of blood vessel cells during angiogenesis. Chersh et al. (Science 1995, 270, 1500) describe anti-.alpha..sub.v .beta..sub.3 antibodies or .alpha..sub.v .beta..sub.3 antagonists which inhibit bFGF-induced angiogenesis processes in the rat eye, which could be useful therapeutically in the treatment of retinopathies.
The Patent Application WO 94/12181 describes substituted aromatic or nonaromatic ring systems and WO 94/08577 describes substituted heterocycles as fibrinogen receptor antagonists and inhibitors of platelet aggregation. EP-A-518 586 and EP-A-528 587 disclose aminoalkyl- or heterocyclyl-substituted phenylalanine derivatives, and WO 95/32710 discloses aryl derivatives as inhibitors of bone resorption by osteoclasts. WO 96/00574 describes benzodiazepines, and WO 96/00730 describes fibrinogen receptor antagonist templates, in particular benzodiazepines which are linked to a nitrogen-bearing 5-membered ring, as vitronectin receptor antagonists.